This invention relates to the field of biomedical testing, and more particularly to the transport, handling and processing of biomedical sample holders such as microplates. Microtiter plates, commonly known as xe2x80x9cmicroplatesxe2x80x9d, facilitate the simultaneous testing (or other processing) of a large number of individual biomedical samples. Microplates have been in common use for decades with a predominant format being a molded plastic plate having 96 sample wells in an 8xc3x9712 rectangular array. Typical well volumes are 200 or 300 microliters, depending upon the manufacturer and model of plate, although other volumes may be provided for specific uses. A proposed standard, designated xe2x80x9cMicroplate 96-Well Standardxe2x80x9d (MP96) has been promulgated by The Society for Biomolecular Screening, as published in Journal of Biomolecular Screening, Volume 1. Number 4. 1996, the disclosure of which is incorporated therein by reference. A microplate which meets the general dimensional requirements of the standard is designated MP96-3. Typically, each microplate manufacturer will also provide a compatible lid. A typical lid comprises a generally rectangular flat planar top surrounded by a flange depending from the top along its sides and edges.
Automated handling of microplates has become an important criterion in their design. It is therefore desirable to provide a microplate lid configuration that facilitates use with automation. Specifically, it is desirable to provide a lid that facilitates automatic stacking and unstacking of lidded microplates, automatic stacking and unstacking of lids without microplates, and automated installation and removal of lids from microplates.
In one embodiment, the invention is directed to a lid which is the unitarily formed combination of a substantially flat, generally rectangular top having first and second pairs of opposite sides and a flange, depending from the top along the first and second pair of sides, the flange bearing at least one recessed area along each of the first pair of sides, the recessed area extending into the top.
Some implementations may include one or more of the following: (1) each side of the first pair of sides may have two such recessed areas: (2) each side of the second pair of sides may have at least one recessed area extending toward the top: (3) each side of the second pair of sides may have one recessed area extending toward but not reaching the top.
In one embodiment, the flange may bear two recessed areas along each of the first pair of sides extending into the top and two recessed areas along each of the second pair of sides extending into the top, with a third recessed area along each of the second pair of sides, between the two recessed areas that extend into the top on such sides, but not reaching the top. The three recessed areas of each of the second pair of sides may be contiguous and the third recessed area may have a substantially straight leading edge. The lid may have a sealing feature for sealing to the top of the microplate and the sealing feature may comprise a substantially continuous lip depending from the lower surface of the top slightly inboard of the sides and uninterrupted by any of the recesses.
A further embodiment of the invention is directed to a process for adding to and removing from a stack of lidded microplates. The initial lowermost microplate in the stack is supported at a first height by a pair of opposite, inwardly-directed support features of a stacking/unstacking machine, each remaining microplate in the stack resting atop the lid of the microplate immediately below. The process may include the steps of adding an additional microplate to the stack as a new lowermost microplate by elevating the additional microplate with an elevator from below the stack until the lid supports the initial lowermost microplate, the support features being accommodated by a pair of opposite, inwardly-directed recesses in the lid of the additional microplate. The support features are separated to allow passage of the additional microplate and the additional microplate is further elevated until it reaches at least the first height, whereupon the support features may be inserted beneath the additional microplate and the elevator lowered so as to disengage the elevator from the stack, leaving the stack supported by the support features and leaving the additional microplate as the new lowermost in the stack. The process may be repeated with further microplates added to the stack in place of the new lowermost microplate.
The invention may further provide for the removal of a microplate from the stack by raising an elevator to engage the lowermost microplate, further raising the elevator to disengage The stack from the support features, separating the support features and lowering the elevator. The support features may be reinserted so that they are accommodated by a pair of opposite, inwardly-directed recesses in the lid of the lowermost microplate and the elevator further lowered so that the microplate above the lowermost microplate is engaged by the support features and becomes the new lowermost microplate as the previous lowermost microplate may be removed.
In a further embodiment, the invention provides for removing a microplate lid by introducing a pair of stop features to a pair of opposite, inwardly-directed recesses in the lid of the microplate so at least a portion of the stop features are positioned directly over at least a portion for the microplate. The lid may be raised with the stop members preventing movement of the microplate so as to permit separation of the lid from the microplate. The raising of the lid may comprise introducing a pair of lifting features into a pair of opposite, inwardly-directed recesses in the lid with at least a portion of the lifting features extending immediately below a portion of the lid.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.